Microstructure and water-swelling mechanism of red-bed mudstone in the Xining region,Northeastern Tibetan Plateau

This paper examines the effect of the microstructure and electrical conductivity(EC)on the swelling ratio and pressure in red-bed mudstone sampled from arid areas in the Xining region in the northeastern Tibetan Plateau.A series of laboratory tests,including swelling experiments,X-ray diffraction(XRD),and scanning electron microscope(SEM),was carried out for mechanical and microstructural analysis.The coupled influence of the EC and microstructural parameters on the expansion ratio and pressure was investigated,and the weight coefficients were discussed by the entropy weight method.The results revealed an increasing exponential trend in EC,and the maximum swelling speed occurred at an EC of approximately 10 μS/cm.In addition,a method for predicting the expansion potential is proposed based on the microstructure,and its reliability is verified by comparing with swelling experimental results.In addition,according to the image analysis results,the ranges of the change in the clay minerals content(CMC),the fractal dimension(FD),the average diameter(AD)of pores,and the plane porosity(PP)are 23.75%-53%,1.08-1.17,7.53-22.45 mm,and 0.62%-1.25%,respectively.Moreover,mudstone swelling is negatively correlated with the plane porosity,fractal dimension and average diameter and is linearly correlated with the clay mineral content.Furthermore,the weight values prove that the microstructural characteristics,including FD,AD,and PP,are the main factors influencing the expansion properties of red-bed mudstones in the Xining region.Based on the combination of macro and micro-analyses,a quantitative analysis of the swelling process of mudstones can provide a better reference for understanding the mechanism of expansion behavior.

High-performance and fabrication friendly polarization demultiplexer

A compact and fabrication friendly polarization demultiplexer(P-DEMUX) is proposed and characterized to enable wavelength-division-multiplexing and polarization-division-multiplexing simultaneously. The proposed structure is composed of a polarization-selective microring resonator in ultrathin waveguide and two bus channels in the silicon nitridesilica-silicon horizontal slot waveguides. In the slot waveguide, the transverse electric(TE) mode propagates through the silicon layer, while the transverse magnetic(TM) mode is confined in the slot region. In the designed ultra-thin waveguide, the TM mode is cut-off. The effective indexes of the TE modes for ultrathin and slot waveguides have comparable values. Thanks for these distinguishing features, the input TE mode can be efficiently filtered through the ultra-thin microring at the resonant wavelength, while the TM mode can directly output from the through port. Simulation results show that the extinction ratio of the proposed P-DEMUX for TE and TM modes are 33.21 dB and 24.97 dB, and the insertion losses are 0.346 dB and 0.324 dB, respectively, at the wavelength of 1551.64 nm. Furthermore, the device shows a broad bandwidth(> 100 nm) for an extinction ratio(ER) of > 20 dB. In addition, the proposed P-DEMUX also has a good fabrication tolerance for the waveguide width variation of-20 nm≤ △w_(g)≤ 20 nm and the microring width variation of -20 nm≤ △w_(r) ≤20 nm for a low insertion loss of < 0.75 dB and low ER of <-18 dB.

Low-cost hybrid integrated 4 × 25 GBaud PAM-4CWDM ROSA with a PLC-based arrayed waveguide grating de-multiplexer

We demonstrate a low-cost hybrid integrated and compact 100 GBaud four-lane coarse wavelength division multiplexing (CWDM) receiver optical sub-assembly (ROSA) based on an arrayed waveguide grating de-multiplexer in the O band. To achieve the horizontal light coupling between the planar light-wave circuit (PLC) based arrayed waveguide grating de-multiplexer and photodetector array, a 42°polished facet is applied for total reflection.A flexible printed circuit with high-frequency coplanar waveguides is used for a power supply of trans-impedance amplifier and signal transmission.The fabricated CWDM ROSA module, whose size is 18mm×22mm×6mm, shows a 3 dB bandwidth of 21.2,18.4,19.6,and 19.3 GHz,respectively,in each lane. The overall symbol error rates are at a magnitude of 10^-7 for 25 GBaud four-level pulse amplitude modulation (PAM-4) transmission with an average input optical power of 5dBm.

Arabidopsis shaker pollen inward K^+ channel SPIK functions in SnRK1 complex-regulated pollen hydration on the stigma

Pollen hydration is a critical step that determines pollen germination on the stigma. KINγ is a plantspecific subunit of the SNF-1-related protein kinase 1 complex （SnRK1 complex）. In pollen of the Arabidopsis kinβγ mutant, the levels of reactive oxygen species were decreased which lead to compromised hydration of the mutant pollen on the stigma. In this study, we analyzed gene expression in kinβγ mutant pollen by RNA-seq and found the expression of inward shaker K^＋ channel SPIK was down-regulated in the kinβγ /pollen. Furthermore, we showed that the pollen hydration of the Arabidopsis spik mutant was defective on the wild-type stigma, althoughthe mutant pollen demonstrated normal hydration in vitro. Additionally, the defective hydration of spik mutant pollen could not be rescued by the wild-type pollen on the stigma, indicating that the spik mutation deprived the capability of pollen absorption on the stigma. Our results suggest that the Arabidopsis SnRK1 complex regulates SPIK expression, which functions in determining pollen hydration on the stigma.

Towards an understanding of plant reproductive isolation:uncovering the species-specific signal for pollen tube guidance

Fertilization produces diploid zygote as the initiation of new diploid organism by fusing two haploid gametes(sperm and egg cell).Different from animals,plants in angiosperms produce immobile sperms in pollen/pollen tube(male gametophyte).Whereas,the egg cell is located in the female gametophyte(embryo sac)that consists of two female gametes(egg and central cells)and accessory cells(synergids and antipodals).Embryo sac is embedded in the ovule of ovary,which is an enlarged basal portion of the pistil.The growth of pollen tube provides a strategy for the immobile sperm approaching the egg cell.After pollination,pollen germinates at the surface of the stigma and produces pollen tube.It grows through the transmitting tract of the style and emerges from it to enter the ovary in response to certain attracting cues from the ovule.